1. Field of the Invention
The present invention generally relates to an audio visual (AV) system, a content directory management system thereof, and a content directory management method thereof, and more particularly, to a distributed AV system, a content directory management system thereof, and a content directory management method thereof.
2. Description of Related Art
Nowadays, ever-increasing multimedia data is shared between digital devices through the Internet along with the development of Internet technology and the generation of digital and web-enabled household appliances. Thus, more convenient digital content sharing mechanisms, such as the universal plug and play (UPnP) technique, are developed in order to meet users' requirement.
The UPnP technique is a standard promulgated by the UPnP forum which is lead by the Microsoft Corp., and a peer-to-peer network structure especially designed for smart devices, wireless devices, and computers is provided in the UPnP technique. According to the UPnP technique, data transmission and control can be carried out between different devices through the Internet regardless of where the devices are located. A distributed and open network structure is provided by the UPnP technique, and the network structure has the functions of zero-configuration and automatic discovery of other devices. With the UPnP structure, a device can dynamically join a network, automatically obtain an Internet protocol (IP) address from the network, detect other devices in the network, share its resources over the network, and obtain resources from other devices in the network.
UPnP audio visual (AV) is a set of standards established based on the UPnP technique regarding the transmission of AV data. Generally, an AV system having the structure of UPnP AV includes a media server, a media renderer, and a control point. The media server is a medium used for storing AV contents, and the AV contents can be selected by a user and played in a selected media renderer. The user can select the AV contents provided by the media server through a user interface of the control point and select a media renderer for playing the selected AV content. The control point sets the media server and the media renderer by issuing UPnP actions so as to allow the media server and the media renderer to transmit AV contents using a transmission protocol (for example, HTTP GET or RTP, etc) and a content format (for example, MPEG2, MPEG4, MP3, or WMA, etc) supported by both the media server and the media renderer, so that the AV contents can be transmitted by the media server directly to the media renderer without: delivering by way of the control point.
The UPnP technique allows different devices to be plugged and played on a network and to share resources over the same. However, along with the diversification of AV content storage devices (i.e. the media servers), it is difficult and inconvenient to those users who are not familiar with computers to read the AV contents distributed in different AV content storage devices when the content directories of the devices are all different. Thus, how to effectively integrate the content directories of different AV content storage devices is one of the most important subjects for implementing a distributed AV system based on a peer-to-peer network.
According to the U.S. Patent No. US-2003/0046703, a primary media server is appointed among a plurality of media servers and an aggregator module and a categorizer module are disposed in the primary media server. Besides, a contributor module is disposed in each of the media servers, wherein the contributor module monitors its own AV content and provides content information related to its own AV content to the primary media server. The aggregator module and the categorizer module of the primary media server combine and categorize the content information provided by the contributor modules of the other media servers. Accordingly, a user can obtain all the AV contents in the network by querying the aggregator module of the primary media server. According to the U.S. Patent No. US-2004/0193609, a primary media server is appointed among a plurality of media servers, and a control point module is embedded in the primary media server. Content information provided by the other media servers are discovered and browsed by using the control point module, and all the content information is then combined by using a master content directory service (MCDS) module of the primary media server. Thus, a user can obtain all the AV contents by directly handshaking with the MCDS module of the primary media server.
As described above, in the conventional content directory management techniques, a media server is appointed as a primary media server and the content directories of other media servers are integrated by this primary media server.